The World Health Organisation (WHO) declared on Thursday (Jan 30) that the coronavirus epidemic in China now constitutes a public health emergency of international concern (PHEIC).

The WHO first introduced PHEIC as part of the 2005 International Health Regulations after the Sars virus in 2003.

Sars was recognised as a "global threat" by the WHO in mid-March 2003. It infected about 8,000 people worldwide and killed 774 people over seven months.

Dr Tedros Adhanom Ghebreyesus, WHO director-general, announced the decision after a meeting of its Emergency Committee, an independent panel of experts, amid mounting evidence of the virus spreading to some 18 countries.

Dr Tedros told a news conference in Geneva that recent weeks have witnessed an unprecedented outbreak which has been met by an unprecedented response.

"Let me be clear, this declaration is not a vote of no confidence in China," he said.

"Our greatest concern is the potential for the virus to spread to countries with weaker health systems," he added.

The WHO defines a global health emergency as an "extraordinary event" that is "serious, unusual or unexpected".

Here's what you need to know about this latest development:

What happens when WHO declares global emergency?

The declaration aims to prevent or reduce the cross-border spread of disease while averting needless obstruction of trade and travel.

It gives the WHO capabilities to hasten the response of governments and organisations globally that are rushing to contain an outbreak. It also tells the world that the outbreak is a serious health emergency.

Temporary recommendations for the national health authorities around the world would be included, such as stepping up their monitoring, preparedness and containment measures.

The WHO does not have legal authority to sanction countries, but it could ask governments to provide scientific justification for any travel or trade restrictions that they impose in the event of an international emergency.

The declaration also gives the WHO the ability to put travel advisories in place, and is a chance for WHO to implement "non-binding but practically and politically significant measures that can address travel, trade, quarantine, screening, treatment.

The WHO can also set global standards of practice", the organisation tweeted.

What does it mean for other countries?

With this declaration, the WHO does not unnecessarily restrict travel and trade to China, but it supports nations with weaker health systems.

The declaration also aims to accelerate the development of vaccines and treatments, while stopping the spread of rumours and misinformation.

Under the global emergency status, countries should work to treat those who are already sick while limiting the spread of the virus.

Countries should share knowledge with the WHO and other countries affected, and work together "in a spirit of solidarity and cooperation".

The designation pushes nations to coordinate funding, personnel and other resources, and helps countries persuade residents to follow health recommendations.

Under the designation, the WHO is able to review public health measures carried out by countries to ensure they meet proper health standards.

These recommendations are not enforceable, but there is pressure on countries to follow them, as member states are bound by the WHO's 2005 International Health Regulations.

Why didn't the WHO declare Wuhan coronavirus as a global emergency earlier?

In the past, the WHO came under fire for raising the alert too soon as well as too late. The last respiratory illness to trigger a health emergency was the flu pandemic of 2009, which caused widespread alarm but ended up being relatively mild.

The WHO's Emergency Committee, a group of infectious-disease experts, last week delayed a decision on whether to make the emergency declaration.

The WHO move may disappoint Beijing, which had expressed confidence it can beat the "devil" virus.

What are the past instances of PHEIC?

Declaration of a public health emergency of international concern is rare.

Only five have been declared in the past decade: The H1N1 virus that caused an influenza pandemic, 2009; West Africa's Ebola outbreak, polio, 2014; Zika virus, 2016; and the ongoing Ebola outbreak in the Democratic Republic of Congo, 2019.